This invention relates to centrifugal separators for separating solid contaminants from a liquid supplied thereto at elevated pressure and in particular relates to operating and maintaining such a centrifugal separator with respect to a machine in which said liquid is contained and flows.
United Kingdom patent specification no. GB-A-2311239 describes a self-powered centrifugal separator, that is, one having a separation rotor which is rotated by the pressure of the liquid supplied to and cleaned thereby, having such a separator rotor contained in a housing defined by separable base and cover parts and discusses the potential problems of inadvertent removal of the cover from the base. The patent specification proposes the inclusion of valve means to divert the elevated pressure supply within the separator to permit such removal without interrupting the supply per se and, also, the provision of a mechanical interlock between a manually operated handle of the valve means and the housing cover which impedes said removal until the valve means is operated to divert the liquid supply from the separation rotor.
As discussed therein, it is a feature of that and other designs of centrifugal separator that the liquid is supplied at elevated pressure to the separation rotor through an axle on which the rotor is mounted for rotation and which axle is disposed between the base and usually also the cover.
The supply is often arranged to exert an axial force on the rotor to overcome gravity so that the cover not only defines a housing to contain liquid discharged from the rotor but also serves to constrain/retain the rotor axially when supplied with liquid and subjected to such axial force.
It has been found that inadvertent removal of the cover without shutting off the elevated pressure supply to the rotor risks having the rotor itself being lifted from the base by the applied pressure and detached, and indeed launched as a projectile, as well as uncontrolled discharge of the liquid.
Whereas the construction of centrifugal separator described in the aforementioned patent specification, that is, the separator rotor being mounted on an elongate stationary spindle fixed to the base, makes it possible for the supply pressure per se to lift the rotor completely clear of the spindle the instant that the cover is separated from the base, it will be appreciated that there are many other configurations of axle means for mounting such separation rotor between base and cover which may be more susceptible to such detachment of the rotor by supply pressure. Particularly susceptible is the type of rotor mounting arrangement in which the rotor is located and mounted with respect to each of the base and cover parts by relatively short stub-axle engagement and in which, if the cover is inadvertently removed, there is little to keep the rotor, particularly if spinning, from instantaneously detaching completely from the base.
In some centrifugal separator designs, it may not be possible to provide a valve arrangement in the separator itself to interrupt the liquid supply to the rotor or rotor mounting means, not only increasing the risk of inadvertent removal of the cover but also making it more difficult to provide a physical interlock against cover removal. Furthermore, even when such a valve for interrupting the liquid supply to the rotor mounting means is provided within the separator, it may be inappropriate to arrange for a manual interlock which prevents removal of the cover, or impracticable because of the necessity to manually overcome the interlock each time the valve means is operated, and even when it is intended to remove the cover.
It is an object of the present invention to provide an improved centrifugal separator with an arrangement for hindering unintentional ejection of the separator rotor.
Another object of the invention is to provide a centrifugal separator with a simple and unobtrusive means of guarding against inadvertent cover removal.
According to the present invention a centrifugal separator of solid contaminants from a liquid supplied thereto at elevated pressure comprises a housing having a base part and a cover part releasably secured with respect to each other and containing a separation rotor, the separation rotor being contained between the base and cover being mounted with respect thereto by spindle means, rotatable about an axis extending between the base and cover and displaceable along the axis limited by said base and cover, the centrifugal separator being characterized by rotor restraining means comprising a restraining surface forming part of, or carried by, the rotor extending radially and circumferentially of the rotor and facing away from the base, and abutment means carried by the base, having an abutment surface overlying the restraining surface at or beyond said limit of axial displacement of the rotor from the base permitted by the cover, operable to prevent further axial displacement of the rotor away from the base in the absence of limitation by the cover.